Typical prior control systems for this class of baler have relied upon mechanical sensors which activate a hydraulic control circuit for cylinders that control the size of the orifice, such sensors normally activating the circuits to either relieve or add fluid pressure depending upon the extent to which the sensors can penetrate the forming bale. In other words, the "tightness" or density of the forming bale results in the sensor being physically positioned in such a way that it performs an appropriate valving function so as to either further pressurize or depressurize the squeeze cylinders.
However, systems of this type rely upon very localized "readings" of bale density and, thus, may not accurately reflect the overall or average density of the bale being formed. Hence, the degree of uniformity of density throughout the bale may suffer.